1. Field of the Invention
This invention relates to an optical shutter in which a magnetic field is applied in a direction perpendicular to that of the light transmission to a magneto-optical material having a light transmissibility and exhibiting a magneto-optical effect, the intensity of the magnetic field being adjusted to control an amount of light propagating through the magneto-optical material.
2. Description of the Prior Art
In applications where a color representation is performed by controlling the balance of three colors, i.e., red, green and blue, or where a shorter wavelength range than the visible light range is utilized, for example, liquid crystal shutter arrays together with a cheap source of white light are advantageous because it is difficult to obtain laser diodes (LDs) or light emitting diode (LEDs) operable in a shorter wavelength range. Liquid crystals, though they had the problem of a low response speed, have recently had their response rate improved considerably by the discovery of ferroelectric liquid crystals and the improvements of the driving systems. There have, however, been problems in that the range of the operating temperature of the liquid crystals is very limited, and that a desired density level has not been properly realized.
Although various other types of optical shutters having also been discussed, no development of a cheap, stable and high-speed optical shutter array has, at present, been attained. This may have acted as an impediment to the development of printers, scanning systems and highly accurate display units.
General advantages (A) and disadvantages (B) of the optical shutters, such as liquid crystal shutters, and so-called active devices represented by LDs and LEDs will be pointed out below.